Zn及固溶时效对Mg-4Al-2Ca合金组织和性能的影响

Effect of Zn and Solution and Aging on Microstructure and Properties of Mg-4Al-2Ca Alloy

通过Mg-4Al-2Ca-xZn系镁合金的设计,研究添加不同含量的Zn对合金微观组织及力学性能的影响。分析得出,铸态Mg-4Al-2Ca合金组织主要由α-Mg、β-Mg17Al12相和少量Al2Ca相组成;当合金中添加2%、4%和6%的Zn后,随着Zn含量的增加合,金的初生相α-Mg变化明显,合金组织中Al2Ca相增加,形成了Mg32(Al,Zn)49相、MgZn相和少量Mg5Zn2Al2化合物;在Zn含量为6%时,合金的初生相α-Mg细化明显,且具有等轴状形态。在时效时间相同的情况下,Zn元素的增加使α-Mg相细化,在相界处析出相减少。经过340℃保温20 h固溶后,在180℃进行一系列的时效处理结果的分析表明,时效72 h时,Mg-4Al-2Ca-xZn(x=0,2,4,6)合金的硬度都达到最大值,分别为72.9、75.1、80.7和83.9 HB,硬度值随Zn含量的增加而增大。

In order to research the influence of Zn on microstructure and mechanical properties of alloys, Mg-4Al-2Ca-xZn alloys were designed by adding Zn alloying element to the alloy. The important results show that the microstrueture of the as-cast Mg-4Al-2Ca-xZn （x=0, 2, 4, 6） alloy without Zn is mainly composed of α-Mg, 13-MglTAl12 and trace of Al2Ca. Adding Zn（2%, 4%, 6%） to the alloy, Al2Ca phase increases in the microstructure; Mg32（Al, Zn）49, MgZn phases and a small amount of MgsZn2Al2 compounds are found in the microstructure; With Zn increasing, the primary α-Mg phase for the alloy is significantly refined. When Zn content is 6%, the primary ct-Mg phase for the alloy is refined with equiaxed morphology. In the case of the same aging time, the increase of Zn element greatly refined the a-Mg phase, and phase boundary precipitates gradually reduced; Aging at 180 ~C, the results show that when the aging time is 72 h, the hardness of Mg-4Al-2Ca-xZn （x=0, 2, 4, 6） alloy reaches 72.9 HB, 75.1 liB, 80.7 lib and 83.9 HB with x increasing, respectively. In the case of the same aging time, the hardness of Mg-4Al-2Ca-6Zn alloy is the largest. The hardness for the Zn-containing Mg-4Al-2Ca alloy is generally higher than that of no Zn -containing of Mg-4Al-2Ca alloy.